FORMABILITY OF ALUMINUM 1050A AT HIGH TEMPERATURES: NUMERICAL MODELING AND EXPERIMENTAL VALIDATION

Abstract

THE SHEET METALS SUCH AS 1050A ALUMINUM ARE PRONE TO LARGE PLASTIC DEFORMATION DURING FORMING PROCESSES. THE PURPOSE OF THE STUDY IS TO INVESTIGATE THE THERMOMECHANICAL BEHAVIOR COUPLED TO THE DUCTILE DAMAGE. A MODIFIED SWIFT MODEL COUPLED WITH AN ISOTROPIC DUCTILE DAMAGE AND THERMAL EFFECTS WAS USED. THE FORMING PARAMETERS ARE INTRODUCED USING THE MODIFIED SWIFT MODEL COEFFICIENTS AND THE ERICHSEN INDEX. AN INVERSE IDENTIFICATION PROCEDURE IS APPLIED TO THE RESULTS OF THE MODIFIED NON-HOMOGENEOUS ERICHSEN TEST. BULGE TEST IS THEN USED TO VALIDATE THE IDENTIFIED PARAMETERS OF THE CONSTITUTIVE MODEL OF 1050A ALUMINUM ACCOUNTING FOR THE THERMAL GRADIENT EFFECT. FURTHERMORE, NUMERICAL SIMULATIONS BY MEANS OF ABAQUS/STANDARD ALLOWED THE MODELING OF ERICHSEN TEST. RESULTS ARE UTILIZED TO CORRELATE THE ERICHSEN INDEX AND CRITICAL PLASTIC STRAIN.

ERICHSEN TEST (PUNCH FORCE VS DISPLACEMENT) RESULTS WERE OBTAINED BY EXPERIMENTAL TESTING AND SIMULATION WITH ABAQUS/STANDARD TO BUILD THE OBJECTIVE FUNCTION FOR THE OPTIMIZATION SCHEME. PLASTICITY FLOW PARAMETERS AND DUCTILE DAMAGE VARIABLES OF ALUMINUM 1050A WERE FIRST IDENTIFIED USING A PART OF THE ERICHSEN TEST RESULTS (FOR TEMPERATURES FROM 20 °C TO 200 °C) AND CORRELATED TO TEMPERATURE. THE REMAINING PART OF ERICHSEN TEST ALONG WITH BULGE TEST RESULTS WERE UTILIZED FOR VALIDATION. THE NUMERICAL APPROACH ALLOWED THE DETECTION OF FAILURE ZONES WITH RESPECT TO THERMAL GRADIENT INDUCED BY HEAT EXCHANGE. WITHIN THE ISOTHERMAL CONDITION, EQUIVALENT STRESSES AND STRAINS FOR 1050A ALUMINUM WERE OBTAINED BY SIMULATIONS AND EXPERIMENTAL DATA.